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ABOUT THIS IMAGE:

The images and illustration reveal that the Andromeda Galaxy's (M31's)
core is composed of a ring of old, red stars and a newly discovered disk
of young, blue stars. The disk is trapped within a supermassive black
hole's gravitational field. The mass of Andromeda's monster black hole
is 140 million times greater than that of our Sun.

The illustration at bottom, right shows the structure of Andromeda's
unusual core and is based on Hubble images of the region. The disk of
blue stars is nested inside the larger ring of red stars. The tiny black
dot within the blue disk is the monster black hole.

Astronomers deduced the structure of Andromeda's core from Hubble images
taken over the past decade. The image at upper, right, taken with the
Wide Field and Planetary Camera 2, shows that the galaxy appears to have
two cores. Normal galaxies only have one core. Astronomers now believe

that Andromeda has one core. The two bright blobs are actually the ring
of red stars and the disk of blue stars. In fact, the bright blob on the
right has a bluish cast.

The image at left is a view of the entire Andromeda Galaxy. The active
core is in the center of the galaxy. Andromeda is 2.5 million
light-years from Earth.